When protecting equipment, a layered or tiered approach yields good results.
The whole service TVSS will have the ability to handle large surges but will start protecting at higher thresholds. The whole service TVSS is valuable for directing the energy under the high spikes to ground, but there is still the energy between nominal service voltage up to the TVSS turnon threshold to worry about.
Therefore, putting more sensitive TVSS units right at the electronics provides additional protection.
The subjective part of all this is determining what is valuable. Obviously the computer and the data stored within is at the top of the list. But, the control chips in the kitchen microwave may have equal value if that's the only way to warm the baby's milk or one has a spiritual need for the morning cup of hot coffee, or the chips in the garage door openner, or the security video recorder.
Once the client lists the most valuable electronic items, one can spec the individual TVSS for each.
For the computers, an additional level of protection can be gained by installing battery standby power systems, providing both TVSS, surge, brown out and blackout protection within the limits of the system.
